Question

A block is randomly selected out of a toy box. The probability of selecting a red block is 0.25. The probability of selecting a block that is both a red block and has a stripe is 0.05.

What is the probability of selecting a red block with a stripe given the toy is a red block?

Enter your answer as a decimal in the box.

Answer 1

The answer is: 0.2

Explanation:

We can use the conditional probability formula:

P(Red block with stripe | Red block) = P(Red block with stripe and Red block) / P(Red block)

We're given P(Red block with stripe and Red block) = 0.05 and P(Red block) = 0.25, so:

P(Red block with stripe | Red block) = 0.05 / 0.25 = 0.2

Therefore, the probability of selecting a red block with a stripe given the toy is a red block is 0.2 or 20% (expressed as a decimal).

Answer 2

0.2

Explanation:

Conditional probability:

P(A | B) = P(A & B) / P(B)

P(striped | red) = P(striped & red) / P(red)

P(striped | red) = 0.05 / 0.25

P(striped | red) = 0.2